Sweetheart, of course you have time. In about a minute more than the time it took you to write that reply you could have listed what time you intend to ingest how much of what substances. You can do that much instead of asking us to research and write a whole article for you.
Not getting the right thing (nitrite vs nitrate)
Or it's confiscated before they get it
Or they can't find a source for the right anti-emetics
Or they don't believe they really can't use OTC anti-emetics
Or they're taking antipsychotics and meto gives them EPS so bad they can't complete the course